Re: [avr-libc-dev] Porting RTEMS patches to avr-libc

[Weddington, Eric]

Hi Cynthia, Joel!

Happy New Year to you both! (We just got done watching the Rose Parade. ;-)

I've added the avr-libc-dev mailing list on this email, so the other developers 
are aware of this and can comment.

First, I think it's great that you're working on this, and I'm all for having 
RTEMS synced with avr-libc, as much as is feasible.

The current release of avr-libc is 1.8.0, though we've been discussing recently 
about fixing a bunch of bugs on HEAD for a future 1.8.1 release. So, I would 
definitely suggest taking a look at porting 1.8.0, or even better making sure 
that it works with HEAD.

Avrtest is what is being used to test with the GCC testsuite. Although I 
thought some work was also being done with simulAVR to make it work with the 
GCC testsuite (perhaps someone else on this list can confirm or correct me if 
I'm wrong).

Additional recommendations: IIRC, there are some specific GCC bugs that are 
avr-rtems specific (though less than a handful). Eventually, you, or someone 
else on the RTEMS team, may want to take a look at those.

Joel and I have talked off and on over the years, and as I understood it, RTEMS 
was using newlib for its C library. Does RTEMS now use avr-libc? Or just a 
portion of avr-libc?

If RTEMS will be using avr-libc on a more permanent basis for the future, then 
perhaps we'll want to make sure that we coordinate testing, bug fixing, etc.

@Joel: I'm curious, do you know of any commercial uses of RTEMS on the AVR 
(that you can mention)? (You can send that to me privately if you need to.)

HTH,
Eric Weddington


> -----Original Message-----
> From: Cynthia Rempel [mailto:address@hidden
> Sent: Tuesday, January 01, 2013 10:43 AM
> To: address@hidden; Weddington, Eric
> Subject: Porting RTEMS patches to avr-libc
> 
> Hi Eric Weddington,
> 
> Happy New Year!
> 
> I'm looking at helping with updating the avr port of RTEMS, and came
> across some of the differences between the RTEMS avr-libc and avr-libc-
> 1.6.8 (the version that is currently in RTEMS).  I went ahead and used
> subversion to generate a patch for avr-libc that should provide some of
> the same functionality that is in RTEMS avr-libc. There are only three
> for the subversion version of interrupt.h, because one of the changes
> appears to already have been applied. It appears that Ralf Corsepius
> address@hidden made the changes to the RTEMS tree on 2011-02-
> 11...
> 
> I do have some questions though:
> Should we still use the avrtest, as opposed to another simulator, such
> as simulAVR?
> Should we look at porting avr-libc 1.8.0, or should we look to port
> another version of avr-libc to RTEMS?
> Do you have any additional recommendations / hints for updating the
> RTEMS AVR port?
> 
> Thanks!
> Cynthia Rempel
> 
> 
> Index: interrupt.h
> ===================================================================
> --- interrupt.h (revision 2303)
> +++ interrupt.h (working copy)
> @@ -228,21 +228,21 @@
>  #  if defined(__AVR_MEGA__) && __AVR_MEGA__
>  #    define ISR_ALIAS(vector, tgt) extern "C" void vector (void) \
>         __attribute__((signal, naked, __INTR_ATTRS)); \
> -       void vector (void) { asm volatile ("jmp " __STRINGIFY(tgt) ::);
> }
> +       void vector (void) { __asm__ volatile ("jmp " __STRINGIFY(tgt)
> ::); }
>  #  else /* !__AVR_MEGA */
>  #    define ISR_ALIAS(vector, tgt) extern "C" void vector (void) \
>         __attribute__((signal, naked, __INTR_ATTRS)); \
> -       void vector (void) { asm volatile ("rjmp " __STRINGIFY(tgt)
> ::); }
> +       void vector (void) { __asm__ volatile ("rjmp " __STRINGIFY(tgt)
> ::); }
>  #  endif  /* __AVR_MEGA__ */
>  #else    /* !__cplusplus */
>  #  if defined(__AVR_MEGA__) && __AVR_MEGA__
>  #  define ISR_ALIAS(vector, tgt) void vector (void) \
>         __attribute__((signal, naked, __INTR_ATTRS)); \
> -       void vector (void) { asm volatile ("jmp " __STRINGIFY(tgt) ::);
> }
> +       void vector (void) { __asm__ volatile ("jmp " __STRINGIFY(tgt)
> ::); }
>  #  else /* !__AVR_MEGA */
>  #  define ISR_ALIAS(vector, tgt) void vector (void) \
>         __attribute__((signal, naked, __INTR_ATTRS)); \
> -       void vector (void) { asm volatile ("rjmp " __STRINGIFY(tgt)
> ::); }
> +       void vector (void) { __asm__ volatile ("rjmp " __STRINGIFY(tgt)
> ::); }
>  #  endif  /* __AVR_MEGA__ */
>  #endif /* __cplusplus */